Low temperature tar tape

ABSTRACT

A TAPE, AND A PROCESS FOR MANUFACTURING IT, WHICH CAN BE USED TO PROTECT PIPE LINES AND WHICH CAN BE APPLIED AT TEMPERATURES AS LOW AS -20*F. AND WHICH HAS A BACKING LAYER AND AN ADHESIVE LAYER CONTAINING AN AMORPHOUS FORM OF COAL TAR KNOWN AS COAL TAR WAX OIL.

May 4, 1971 w. J. OBRIEN ETAL 3,577,269 LOW TEMPERATURE TAR TAPE Filed Oct. 25, 1968 F/G. l2g

\ INVENTORS.

United States Patent O 3,577,269 LOW TEMPERATURE TAR TAPE William J. OBrien, Hamden, Conn., and Raymond E. Downey, Copley, Ohio, assignors to Dart Industries Inc. Filed Oct. 23, 1968, Ser. No. 769,996 Int. Cl. C095 7/02, 7/ 04 U.S. Cl. 117-122 16 Claims ABSTRACT OF THE DISCLOSURE A tape, and a process for manufacturing it, which can be used to protect pipe lines and which can be applied at temperatures as low as 20 F. and which has a backing layer and an adhesive layer containing `an amorphous form of coal tar known as coal tar wax oil.

BACKGROUND OF INVENTION (l) Field of invention (2) Description of prior art Thousands of miles of metallic pipe lines are buried or run along the surface of the ground and are constantly exposed to external corrosion from water, oxygen, and minerals. Various means have been employed for protection of metals exposed to corrosion. Enamel coatings, hot tar, and plastic tapes are a few of the methods that have been employed. One of the best and least expensive methods for protecting buried metallic objects, especially pipe lines, is the use of tar tape. Tar tape is a tape formed from an adhesive composition containing tar upon the surface of a iiexible backing layer. Some of the advantages of tar tapes are as follows:

(1) Tar tapes are insoluble in oils and similar hydrocarbons.

(2) Tar tapes will not disbond under normal current conditions encountered during the cathodic protection of pipe lines.

( 3) Tar tapes have high dielectric strength.

(4) There is no drying time required after tar tapes are applied as is encountered when tar or enamel is utilized.

(5) Tar tapes can be applied with lower labor costs.

(6) When tar tape is used the pipe can be backlled immediately.

(7) There is less clean-up necessary when tar tapes are used.

(8) The logistical problem of handling a coating material is minimized.

(9) Tar tape eliminates equipment used to heat enamel and tar.

(10) Tar tape has excellent resistance to water.

Tar tape, however, has certain disadvantages:

(l) Tar tapes used in the prior art cannot be applied at temperatures below 45 F.

(2) Tar tape, after being applied to pipe, will crack at temperatures below 45 F. if there is pipe movement.

(3) Tar tape used in the prior art has a short shelf life,

generally not exceeding 6 months.

(4) In the manufacture of tar tape used in the prior art, long blending times are necessary when other additives are mixed with the tar.

(5) Tar tapes in the prior art do not have enough of the tar-like aroma desired by the users of the tape.

It is an object of this invention to provide a tape containing tar-like materials which can be applied at temperatures below 45 F. and as low as 20 F.

It is a further object of this invention to provide a tar tape -with superior shelf life.

A still further object of this invention is to provide a tar tape with improved tackiness.

It is still a further object of this invention to provide a tar tape with a stronger tar-like aroma.

It is still a further object of this invention to provide a more eflicient and easier process for the preparation of tar tape.

It is a further object of this invention to provide a tar tape having all of the advantages of the tar tape in the prior art in addition to the above-mentioned improvements.

It is a further object of this invention to provide a tar tape which can withstand pipe movement to temperatures as low as 60 F.

Further objectives of this invention will become apparent in the incorporated drawings, text, and examples.

BRIEF DESCRIPTION OF INVENTION This invention concerns a strip material for covering and protecting pipe lines and other similar objects. The novel Wrapping can be applied at temperatures encountered during the winter months in Northern North America. The strip material has at least two contiguous layers. One of the layers is a flexible sheet material and the other layer is a tacky adhesive material. The adhesion is of sufiicient strength to bond the sheet material to the Object covered and the combined strength of the tacky layer and sheet material is suicient to permit wrapping at various temperatures. The adhesive material contains a non-crystalline hydrocarbonaceous material which will not crack at low ambient temperatures during application of the strip material.

Tar tape incorporating coal tar wax oil in the adhesive material is an example of the above strip material and is usually prepared by blending an adhesive composition containing coal tar wax oil and then applying the composition to a flexible backing. Applicants have discovered that the use of coal tar wax oil instead of tar in the adhesive composition shows unexpected improvement in tar tape. Tar tape having coal tar wax oil incorporated shows marked improvement in many of the properties of tar tape formerly employing coal tar. Tar tapes using coal tar wax oil in accordance with this invention can be applied at Itemperatures below 45 F. and as low as 20 F. Tar tapes prepared in accordance with this invention have a shelf life known to be at least four times as long as tar tapes prepared in the prior art. Tar tapes employing coal tar wax oil in place of at least a portion of the tar used in the prior art shows improved tackiness without the addition of an increased amount of other adhesives. Since the personnel using tar tape Want to be certain that the tape has adequate tar-like material, they prefer tar tapes having a strong tar-like aroma and since coal tar wax oil contains more of the aromatic ingredients which give the aroma of tar, tar tapes employing coal tar wax oil have a strong tar-like aroma. Tar tapes having coal tar wax oil in the formula can withstand some pipe movement down to temperatures as low as 60 F. In addition to the foregoing advantages of tar tapes using coal tar wax oil in place of tar, tar tapes using coal tar wax oil have all of the advantages of tar tapes prepared in the prior art.

It is presently preferred to use in the invention a coal tar wax oil completely obtained from coal tar, preferably by vacuum distillation. The preferred coal tar wax oil has a specific gravity between 1.1 to about 1.3 and is generally about 1.20, is amorphous in character, has an Engler viscosity between about 3 to about 4 seconds and is generally about 3.7 sec., and has a -boiling range as follows:

0-355 12.6%. 04400 50.86%. Above 400 Decomposes The Engler viscosity is found using ASTM Test D-490. The flow of 100 ml. of coal Atar wax oil 'at 80 C. is timed through a standard opening.

In the prior art, processing of adhesives containing tar like materials require-d long mixing times. The present invention greatly reduces process time. When coal tar wax oil is used instead of tar in the preparation of tar tape the mixing time `of the adhesive composition is 4reduced by as much as 65% PREFERRED EMBODIMENT OF THE INVENTION In the preferred embodiment from about to 30 percent of coal tar Wax oil is incorporated in the adhesive composition of tar tape in combination with other adhesive composition ingredients such fillers, additives, plasticizers and the like. The applicants have found the following ingredients to be particularly useful in the manufacture of the tape:

(1) Various compounds such as asphaltic components, can be incorporated as a matrix. A preferred example of such a compound is Atlantic I#100 Resin because it not Ionly acts as a matrix but assists .as a Plasticizer. It is a unique material prepared from petroleum and consists of a special asphaltic cut having a specific gravity at 60 F. of 1.0 to 1.3 and preferably about 1.1-6, a softening point of approximately 95 F., and a boiling range at 2 mm. pressure as follows:

Temperature, F.

Initial 434 10% over 520 30% over 558 50% over 586 70% over 620 All over 656 This special resin has a chromatographic analysis as follow: non-aromatics about 1.4%, aromatics about 94.6%, polar compounds about 4%. It has a Rostler analysis of asphaltenes about 2.5%, N-Base Resin about 31.9%, First acidalins about 50.4%, Second Acidains about 14.4%, parains about 1.1%. In the preferred embodiment from about 10 to 30% of an asphaltic component may be used.

(2) Extenders and fillers can be 'used in the adhesive composition and because of the small particle size a recommended extender is Talc. Any good grade Talc can be 'used but should lhave very low Water absorption.

(3) Plasticizers may be incorporated into the adhesive composition and several recommended plasticizers are dioctyphthalate plasticizer, di-isodecyl adipate plasticizer, and Conoco H-25 plasticizer.

(4) Polymeric materials may be incorporated into the adhesive composition to give added tack and body to the formulation. A preferred polymer is polyvinyl chloride which forms a plastisol with the adhesive composition forming an adhesive composition having a thicker consistency and improved tack. In the preferred embodiment from 10 to 40% polyvinyl chloride is used.

Numerous types of flexible backings for the tar tape can [be used. Some examples of backings which have been successful are polymeric iilrns such as: polyethylene film, polypropylene iilm, polyvinyl chloride film. Glass cloth, paper, and woven and synthetic fabrics have also been found acceptable as flexible backngs. Anti-oxidants and ultra-violet absorbers can be incorporated into the backing to prevent degradation. From 0% to about 10% carbon black has been used to prevent degradation of polyethylene backing; A preferred backing is eleetrostatically treated 4 polyethylene film. Electrostatically treated polyethylene film has adequate strength and flexibility. The adhesive composition adheres to the treated surface but easily separates from the untreated surface thus enabling the tape to be easily removed from tape rolls.

BRIEF DESCRIPTION OF DRAWINGS The process employed in the present invention will be more readily understood and the objects and advantages will be more readily apparent When read in conjunction with the accompanying drawings in which:

FIG. 1 is an elevational view in cross section of the blending apparatus used to prepare the adhesive composition which is fed to the calender.

FIG. 2 is a schematic diagram of a calender method of making coal tar tape.

FIG. 3 is a cross-sectional perspective view of the finished tar tape.

DESCRIPTION OF THE DRAWINGS The tar tape of this invention may be prepared using the apparatus shown in FIG. 1. The ingredients are introduced into a container 10 in which there is a mixer 11 having a high-speed dispersion blade system 12 wherein a heated tar containing adhesive formulation is sheared violently as the dispersion blade system rotates at speeds in excess of about 1700 to about 2500 r.p.m. All of the liquid ingredients, preferably heated to a temperature of F., are loaded into the mixing container and the mixer is started at a slow speed. The solid ingredients are loaded into the container in increments. After all of the solid materials are added the mixer speed is increased and the heater 13 is'utilized to raise the temperature of the mix to 300 F. After blending is completed, the stirrer is removed from the molten mix and the mixture is poured into pans and allowed to cool.

From this point the adhesive formulation in the form of slab 2S is fed to the calender rolls 14 and 15, shown in FIG. 2. The calendered film is fed to temperature control roll 16 and is pressed onto treated polyethylene film 17 using silicone rubber pressure roll 18. From the pressure rolls the newly formed tape 1-9 is led upwards to an upper oor or mezzanine for slitting. Before being slit, the tape is placed around a tension or speed control dancer roll 20. The purpose of the dancer roll is to control the tension of the tape coming from the calender and to synchronize the speed of the slitting and winding equipment.

The slitter consists of a hardened steel roll 21 with score cut type rotary cutters 22 in contact therewith. The position of the cutters rwill be adjustable to permit the cutting of |various widths of tape. The slitter will be equipped with a surface Wind mechanism 23 to permit Winding various lengths of rolls at controlled Wind-up tension. The tape is finally Wound on wind-up mandrel 24.

'Ihe finished tar tape will include, as shown in FIG. 3, l; adhesivek composition 26 upon a flexible backing layer EXAMPLES The following examples are illustratives of the invention:

The above formulation was introduced into a special highspeed mixer having a dispersion blade system which rotates at a speed in excess of about 1700 to about 2500 r.p.m. The order of addition of the ingredients to the mixer is important. All of the liquid ingredients such as Atlantic #100 Resin (which is a special asphaltic cut), coal tar wax oil, di-isodecyl adipate plasticizer, di-octyl phthalate Plasticizer and Conoco H-25 plasticizer at a temperature of 180 F., were loaded into the mixing container and the mixer was started. The solid ingredients were added in a preferred order. One-half of the Polyvinyl Chloride Resin was added initially. After 4 minutes of mixing the balance of Polyvinyl Chloride was added in small increments. This requires approximately 4 minutes more mixing time. At this point the rotor speed was increased and the heat of the mix was allowed to build to 290 F. The Talc was then added to the mix in small increments requiring about 5 minutes mixing time for complete incorporation. The temperature was increased to 300 F. This required an additional 4 to 5 minutes at which point the mixer was removed from the molten mix and the mixture was poured into pans and allowed to cool.

From this point the low temperature coal tar mixture in slab form was sent to the calender which applied the controlled lm of the formulation onto a polyethylene sheet.

The low temperature coal tar polyethylene laminate was cooled, wound up in sheet form and later slit into rolls of suitable length and width for pipe line wrapping.

The tape obtained in this example had a shelf life greatly superior to the tar tape prepared in the prior art, could be applied at temperatures as low as -20 F., did not crack with minor pipe movements at temperatures as low as --60 F., had a tar-like aroma, and had tack which was superior to the tack of tar tape prepared in the prior art formulation when coal tar was used instead of coal tar wax oil.

The tape incorporating the above formulation was prepared in accordance with the process of Example 1. The tape obtained in this example again had a shelf life greatly superior to the tar tape in the prior art, could be applied in temperatures as W as I20 F., did not crack with minor pipe movements at temperatures as low as 60 F., had a tar-like aroma, and had tack which was superior to the tack of tar tape prepared in the prior art formulation, when coal tar was used instead of coal tar wax oil.

FORMULATION Example 3 Pounds Polyvinyl Chloride 94.0 Coal Tar Wax Oil 101.0 Atlantic 100l Resin 127.5 DIDA Plasticizer 29.0 DOP Plasticizer 26.5 Conoco H-25 Plasticizer 25.5

Talc 117.5

To a covered 55 gallon drum of Atlantic 100 Resin, 3 band heaters and band heater insulators were applied for a period of 24 to 48 hours. To a 55 gallon drum of coal tar wax oil, sufficient band heaters and insulators were applied to maintain a temperature of 125 to 135 F. Agitation was used during heating. The temperature of the Atlantic 100 Resin was held between 150 and 200 F. for ease of transfer to the mixing drum.

By means of direct weighing (or weight-volume-temperature determinations) the required amount of Atlantic Resin and coal tar wax oil were transferred to the mixing drum. The mixing drum was anchored to a frame and rested on a Calrod heating element. Three band heaters and insulators Were attached around the outside of the drum. A cover was lowered over the mixing drum and an exhaust hose was attached to the cover. Heat was applied to the drum by means of the aforementioned heaters. A long stem thermometer was used to check the temperature of the liquids. The mixer was then started at a low speed.

The required amounts of DOP, DIDA, and H-25 plasticizers were weighed into a common container and were stirred until thoroughly blended.

When the temperature of the blended 100 Resin and coal tar wax oil reached 200 F. the plasticizers were slowly added to the mixing drum. A temperature drop occurred and mixing was continued until the temperature of the mix reached 250 F.

With a two-pound capacity scoop, the preweighed polyvinyl chloride resin was slowly added to the mixing drum. The resin was added at the ridge of the mixing vortex. After all of the resin was added the mixing speed was increased to maximum output and mixing was continued for five minutes. With a two-pound capacity scoop the Talc was added at the ridge of the vortex.

Mixing was continued until a smooth blend was obtained when a sample was drawn down on a plate. The mixture was then drawn off through a screened spigot into paper lined trays, which were then set aside to cool. After cooling, the slabs of the low temperature coal tar mixture were sent to calender rolls which formed a film of the adhesive mixture having a thickness of 11 mls. The calendered lm was then fed to a temperature control roll and pressed onto treated polyethylene lm using a silicone rubber pressure roll. From the pressure rolls the newly formed tape was lead to a tape slitter and the tape was wound into finished rolls.

The tape obtained in this example had a shelf life greatly superior to the tar tape prepared in the prior art, could be applied in temperatures as low as 0 F., had a tack which was superior to tar tape prepared in the prior art formulation when coal tar was used instead of coal tar wax oil, and was stable to air temperatures as high as F.

What is claimed is:

1. A flexible strip material adapted for application to objects exposed to atmospheric underground, underwater or other corrosive conditions, said flexible strip material comprising a ilexible backing layer and an inner layer of an adhesive composition including an amorphous coal tar wax oil, said coal tar wax oil having a specific gravity of from about 1.1 to about 1.3, having a boiling range above 300 C. and having an -Engler specific viscosity of from about 3 to about 4 seconds for 100 ml. at about 80 C., said flexible backing layer being suitable for the receipt of said inner layer of said adhesive composition.

2. A ilexible strip according to claim 1 wherein said coal tar wax oil is obtained entirely from coal tar by vacuum distillation and yields below about 15% distillate at 355 C. at atmospheric pressure.

3. A flexible strip according to claim 1 wherein about 12.6% of the wax oil is distilled at atmospheric pressure at 355 C.

4. A ilexible strip according to claim 2 wherein said coal tar wax oil decomposes at 400 C.

5, A flexible strip comprising a flexible backing layer and an inner layer of an adhesive composition including an amorphous coal tar wax oil, said coal tar wax oil being obtained entirely from coal tar by vacuum distillation and having a specilic gravity of from about 1.1 to about 1.3, having a boiling range above 300 C. and having an Engler specic viscosity of from about 3 to about 4 seconds for 100 ml. at about 80 C.

6. A flexible strip as set forth in claim 5 in which said ilexible backing is a water resistant polymeric film.

7. A iieXible strip as set forth in claim in which said flexible backing is polyethylene.

8. A flexible strip as set forth in claim 5 in which said polyethylene contains up to ten percent carbon black.

9. A flexible strip as set forth in claim 5 in which said ilexible backing is paper.

10. A exible strip as set forth in claim 5 in which said flexible backing is a Woven fabric.

11. A flexible strip according to claim 5 wherein said adhesive composition further includes an asphaltic component.

12. A exible strip according to claim 1'1, wherein said asphaltic component has a specic gravity of from 1.0 to 1.3 and a boiling range at about 2 mm. pressure of about 400 F. to 700 F., said asphaltic component comprising about 85% to about 100% aromatic compounds, about 0 to about polar compounds and about 0 to about 5% other non-aromatics.

13. A flexible strip according to claim 5 wherein said adhesive composition further includes polyvinyl chloride.

14. A iiexible strip according to claim 5 wherein said adhesive composition further includes an asphaltic component and polyvinyl chloride, said composition including about 10-30% of said coal tar wax oil, 10-30% of said asphaltic component and 10-40% of said polyvinyl chloride.

References Cited UNITED STATES PATENTS 2,478,654 8/1949 Croyere 208--23 2,635,085 4/1953 Gonnard 117--168 2,697,697 12/1954 Beck 260-28.5D 2,883,354 4/1959 Sperling 260-28.5D 2,919,059 12/1959 Sporka 117-138.8E 3,219,064 10/1965 Downey 260-28.5D 3,304,192 2/ 1967 Barrett 208-23 3,388,723 6/1968 McNulty 117-138.8

ALFRED L. LEAVITT, Primary Examiner M. F. ESPOSITO, Assistant Examiner U.S. C1. X.R. 

